Publikationsliste

Title

Modeling the interfacial tension dependence on composition and stiffness of nonionic surfactants on liquid-liquid interfaces

Date

20.04.2017

Number

53710

Abstract

Adsorption and self-assembly of linear polymers on liquid–liquid interfaces is modeled in this work by means of extensive Molecular Dynamics simulation. By varying the size, concentration, stiffness, and composition of nonionic surfactant, we examine their impact on surface tension · at the phase boundary between two immiscible liquids, e.g., “oil” and “water”. Our results indicate that alternating AB-copolymers are much more efficient than homopolymers or diblock copolymers in reducing ·. This efficiency of the tested linear polymers is not very sensitive with respect to surfactant chain length, except for the AB-diblocks, where the shortest chains are also the most efficient ones and rival the alternating architecture in reducing surface tension. In contrast, increasing stiffness of all surfactants is found to make them significantly less efficient with regard to ·-reduction. Stiffer chains are also found to form rafts, and at higher concentration, quasi-crystalline blocks at the liquid–liquid interface leaving big interfacial area devoid of surfactants. For the shorter rigid surfactants one observes gradual tilting during their self-assembly into bundles whereby the tilt angle increases substantially with increasing coverage.